A butterfly is an insect with four large, colorful wings covered in tiny scales that create brilliant patterns. Butterflies start life as caterpillars, then transform completely inside a chrysalis through a process called metamorphosis. When they emerge, they have wings and can fly. They feed on flower nectar using a long, straw-like tongue called a proboscis.

Butterflies are found on every continent except Antarctica. Some, like the monarch butterfly, migrate thousands of miles each year. Different species have wildly different wing patterns: some look like leaves for camouflage, others display bright warning colors, and some even have spots that look like eyes to scare off predators.

People also use “butterfly” to describe nervous feelings in your stomach. When you feel butterflies in your stomach before giving a speech or meeting someone new, it's that fluttery, anxious sensation. The image works because those nervous feelings can feel as light and unpredictable as butterflies flapping around inside you.

In swimming, the butterfly is a challenging stroke where both arms swing forward together over the water while your legs kick in a dolphin-like motion. It's one of the hardest swimming strokes to master but also one of the most impressive to watch.